1. Field of the Invention
This invention relates to a writing pen using a replaceable ball point pen cartridge which is locked into the pen, and, more particularly, to a pen which includes a removable point which locks the ball point pen cartridge within the pen and which requires a wrench or key to remove the tip to replace the cartridge.
2. Description of the Prior Art
A chronic problem in business establishments which are frequented by people who must fill out documents, such as banks, post offices, and various types of government organizations, city, state, and federal, is the loss of pens. The business establishments provide pens as writing implements for the convenience of their customers or clientele and, as a result of the continual losses, must replace the pens regularly.
This loss has been alleviated by using a pen holder which may be secured to a counter or desk and by a pen connected to the holder by a stranded cable. The cable type connection replaces pens which use a cord or a bead type chain, both of which may be easily broken or cut. However, unless there is some way to prevent the pen from being taken apart, the ball point cartridge may easily be removed from the pen even though the pen itself may not be taken. It is accordingly necessary to provide a lockable pen.
The next step in preserving the pen for the business establishments was to develop a lock system to prevent the pen from being taken apart without the use of a special tool or key to unlock cooperating parts of the pen. U.S. Pat. No. 3,570,284 discloses such a lock system. The lock system employed in the U.S. Pat. No. 3,570,284 comprises a pen which includes a removable tip and a movable insert in the tip. The barrel or cylinder of the pen includes a circumferentially extending groove, with a matching groove on the tip. A small ball is disposed in the matching grooves to lock the pen barrel and the tip together. The movable insert within the tip includes a detent or groove into which, when the detent or groove is aligned with the grooves in the barrel and in the tip, allows the ball to be moved out of the grooves in the cylinder or barrel and the tip and into the movable insert. This allows the tip to be unscrewed and removed from the barrel for replacing the cartridge.
The movable insert comprises a lock member which is moved into alignment with the ball and the grooves by the employment of a tool which fits over the point of the pen cartridge and is inserted into the tip to move the insert or lock member in order to release the ball.
While the apparatus disclosed in the U.S. Pat. No. 3,570,284 has enjoyed substantial success, there are, nevertheless, limitations. For example, if one were to lose the ball during the process of taking the pen apart to replace a cartridge, the locking feature will be lost. Moreover, the use of the matching grooves among the cooperating parts requires extra machining, which, if eliminated, would substantially reduce the manufacturing costs of the pen apparatus.
The apparatus of the present invention provides means for locking the tip and a cylindrical barrel of a pen together without the use of detents, grooves, or the like, and accordingly is simpler and less expensive to manufacture than the pens of the prior art.